A rotatively driving apparatus includes: a differential rotation amplification mechanism for amplifying differential rotation between a rotating shaft and a drive pinion shaft which are relatively rotatable; a rotor interlockingly rotatable with a amplified differential rotation amplified; and a rotation controlling mechanism for controlling the rotation of the rotor. The rotation controlling mechanism includes a stator for constituting an electric motor together with the rotor, a variable resistor for absorbing electric energy generated by the electric motor by the rotation of the rotor, and a controller for controlling torque transmitted between the rotating shaft and the drive pinion shaft by adjusting the energy absorbed by the variable resistor. The differential rotation amplification mechanism and the rotor are disposed on an identical axis.